An assessment was made of the suitability of optical methods as means of nondestructively evaluating the morphology of collagen in intact leaflets of bioprosthetic valves. The results demonstrate that transmitted polarized light and incident polarized light optics facilitate the imaging of the inherent birefringence of valvular collagen fibers and serve to determine the patterns of collagen configuration and orientation in unimplanted and explanted porcine aortic valvular and bovine pericardial bioprostheses.